//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

// UNSUPPORTED: !stdlib=libc++ && (c++03 || c++11 || c++14)

// <string_view>

// template<class charT, class traits>
//   constexpr bool operator<(basic_string_view<charT, traits> lhs, basic_string_view<charT, traits> rhs);
// (plus "sufficient additional overloads" to make implicit conversions work as intended)

#include <string_view>
#include <cassert>
#include <string>

#include "test_macros.h"
#include "constexpr_char_traits.h"
#include "make_string.h"

template<class T>
struct ConvertibleTo {
    T t_;
    TEST_CONSTEXPR explicit ConvertibleTo(T t) : t_(t) {}
    TEST_CONSTEXPR operator T() const {
        return t_;
    }
};

template<class SV>
TEST_CONSTEXPR_CXX14 bool test()
{
    typedef typename SV::value_type CharT;
    typedef typename SV::traits_type Traits;

    // Test the behavior of the operator, both with and without implicit conversions.
    SV v[] = {
        SV(MAKE_CSTRING(CharT, "")),
        SV(MAKE_CSTRING(CharT, "abc")),
        SV(MAKE_CSTRING(CharT, "abcdef")),
        SV(MAKE_CSTRING(CharT, "acb")),
    };
    for (int i = 0; i < 4; ++i) {
        for (int j = 0; j < 4; ++j) {
            // See http://eel.is/c++draft/string.view#tab:string.view.comparison.overloads
            bool expected = (i < j);
            assert((v[i] < v[j]) == expected);
            assert((v[i].data() < v[j]) == expected);
            assert((v[i] < v[j].data()) == expected);
            assert((ConvertibleTo<SV>(v[i]) < v[j]) == expected);
            assert((v[i] < ConvertibleTo<SV>(v[j])) == expected);

            if (!TEST_IS_CONSTANT_EVALUATED || TEST_STD_VER >= 20) {
                assert((std::basic_string<CharT, Traits>(v[i]) < v[j]) == expected);
                assert((v[i] < std::basic_string<CharT, Traits>(v[j])) == expected);
            }
        }
    }

    // Test its behavior with embedded null bytes.
    SV abc = SV(MAKE_CSTRING(CharT, "abc"));
    SV abc0def = SV(MAKE_CSTRING(CharT, "abc\0def"), 7);
    SV abcdef = SV(MAKE_CSTRING(CharT, "abcdef"));
    assert((abc < abc0def) == true);
    assert((abc < abcdef) == true);
    assert((abc0def < abc) == false);
    assert((abc0def < abcdef) == true);
    assert((abcdef < abc) == false);
    assert((abcdef < abc0def) == false);

    assert((abc.data() < abc0def) == true);
    assert((abc0def < abc.data()) == false);

    if (!TEST_IS_CONSTANT_EVALUATED || TEST_STD_VER >= 20) {
        assert((std::basic_string<CharT, Traits>(abc) < abc0def) == true);
        assert((abc0def < std::basic_string<CharT, Traits>(abc)) == false);
    }

    return true;
}

int main(int, char**)
{
    test<std::string_view>();
#ifndef TEST_HAS_NO_WIDE_CHARACTERS
    test<std::wstring_view>();
#endif
#if TEST_STD_VER >= 11
    test<std::u16string_view>();
    test<std::u32string_view>();
#endif
#if TEST_STD_VER > 14
    static_assert(test<std::string_view>(), "");
#ifndef TEST_HAS_NO_WIDE_CHARACTERS
    static_assert(test<std::wstring_view>(), "");
#endif
    static_assert(test<std::u16string_view>(), "");
    static_assert(test<std::u32string_view>(), "");
#endif

#if TEST_STD_VER > 11
    test<std::basic_string_view<char, constexpr_char_traits<char>>>();
    static_assert(test<std::basic_string_view<char, constexpr_char_traits<char>>>(), "");
#endif

#if TEST_STD_VER > 17
    test<std::u8string_view>();
    static_assert(test<std::u8string_view>());
#endif

    return 0;
}
